Authors: George Rajna
A puzzling neutrino shortfall seems to be due to faulty predictions, not a new particle.  Results from a new scientific study may shed light on a mismatch between predictions and recent measurements of ghostly particles streaming from nuclear reactors—the so-called "reactor antineutrino anomaly," which has puzzled physicists since 2011.  Physicists have hypothesized the existence of fundamental particles called sterile neutrinos for decades and a couple of experiments have even caught possible hints of them. However, according to new results from two major international consortia, the chances that these indications were right and that these particles actually exist are now much slimmer.  The MIT team studied the distribution of neutrino flavors generated in Illinois, versus those detected in Minnesota, and found that these distributions can be explained most readily by quantum phenomena: As neutrinos sped between the reactor and detector, they were statistically most likely to be in a state of superposition, with no definite flavor or identity.  A new study reveals that neutrinos produced in the core of a supernova are highly localised compared to neutrinos from all other known sources. This result stems from a fresh estimate for an entity characterising these neutrinos, known as wave packets, which provide information on both their position and their momentum.  It could all have been so different. When matter first formed in the universe, our current theories suggest that it should have been accompanied by an equal amount of antimatter – a conclusion we know must be wrong, because we wouldn't be here if it were true. Now the latest results from a pair of experiments designed to study the behaviour of neutrinos – particles that barely interact with the rest of the universe – could mean we're starting to understand why.  In 2012, a tiny flash of light was detected deep beneath the Antarctic ice. A burst of neutrinos was responsible, and the flash of light was their calling card. It might not sound momentous, but the flash could give us tantalising insights into one of the most energetic objects in the distant universe. The light was triggered by the universe's most elusive particles when they made contact with a remarkable detector, appropriately called IceCube, which was built for the very purpose of capturing rare events such as this. 
Comments: 36 Pages.
[v1] 2017-04-17 06:22:35
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